The invention pertains to a milling cutter and cutting tools therein that provide improved performance features. More specifically, the invention pertains to a milling cutter that does not leave a burr on the workpiece after the completion of the milling operation and provides an acceptable workpiece surface finish. Furthermore, the invention concerns a method of milling that does not leave a burr on the workpiece after the completion of the milling operation and provides an acceptable workpiece surface finish.
Typically, a milling cutter comprises a milling head that holds a plurality of milling inserts that project forwardly of the forward face of the milling head. In operation, the milling head rotates and then engages the workpiece material so as to mill, i.e., remove material, from the workpiece. Common types of milling operations include face milling, end milling and slotting.
U.S. Pat. No. 4,202,650, to Erickson, for a SHIM LOCK FASTENER; U.S. Pat. No. 4,575,287, to Oshnock et al., for a MILLING CUTTER AND METHOD OF ASSEMBLY THEREFOR; and U.S. Pat. No. 5,292,213, to Massa, for a COUPLING DEVICE FOR HIGH-SPEED ROTATING, illustrate various styles of milling cutters. Furthermore, Kennametal catalog entitled "Kennametal Milling/1987" illustrates a variety of milling cutters and milling inserts.
One problem that exists in some milling operations is the presence of burrs on the milled surface of the workpiece after the completion of the milling operation. In the past, when using cemented carbide milling inserts, both coated and uncoated, the inclusion of a so-called wiper insert on the milling head helped reduce the problem of burrs. In these earlier arrangements, the wiper insert and the milling inserts were made from the same grade of cemented carbide. Furthermore, in these earlier arrangements the wiper insert was of a different geometric shape than the milling inserts.
In milling materials such as aluminum-silicon alloys, one type of milling insert comprises a cemented carbide substrate having a thin film diamond layer deposited thereon by chemical vapor deposition (CVD) techniques. In the past, when milling aluminum-silicon alloys using thin film diamond milling inserts there has existed a problem of burrs remaining on the milled surface of the workpiece. The presence of such burrs on the milled surface of the workpiece is undesirable. It would thus be desirable to provide a milling cutter that can mill a workpiece such as an aluminum-silicon alloy so as to not leave a burr on the milled surface thereof.
In the past, when milling a workpiece made of an aluminum-silicon alloy there has existed the problem of providing a milled surface with an adequate surface smoothness. This problem has been especially apparent when using thin film diamond milling inserts primarily because the surface of the diamond coating is microscopically rough faceted and this roughness causes rougher workpiece surface finishes. It would thus be desirable to provide a milling cutter than can mill a workpiece such as an aluminum-silicon alloy so as to provide a milled surface with an acceptable smoothness.